M-8 Beehive Spring Rocker Shim Conversion System
Manufacturing valvetrain for 80 years and two generations, this new M-8 beehive spring rocker shim conversion system by Pacifica, California based Kibblewhite Precision Machining (KPMI) is an innovative design that adds a 9.5 mm hardened steel shim between the valve tip and rocker arm.
This increases allowable rocker wipe area for maximum valve lift - up to 0.625" valve lift compatibility.
They are offered with either titanium or H.T. steel retainers and include heavy duty 9° H.T. steel keepers, 9.5 mm steel shim, red Viton seals and a H.T. steel base washer.
The kit utilizes the proven KPMI 0.625" beehive spring and a lightweight retainer that houses a standard 9.5 mm hardened steel shim. The rocker arm rides directly on the shim surface and the 9.5 mm diameter significantly increases the allowable rocker wipe area. This provides the ability to utilize larger lift cams than previously able to run on a 6 mm valve stem. Additionally, the rocker shim thickness can be varied to adjust effective stem protrusion.
When larger camshafts are used, and valvetrain acceleration values increase, KPMI strongly recommends running titanium valves for maximum performance. To maximize shim contact in the retainer, KPMI recommends "tipping" (shortening the valve tip). There is anticipated to be a roughly 0.100" increase in effective stem protrusion with the use of the shim.
KIBBLEWHITE PRECISION MACHINING